The present disclosure relates to a battery module, an electronic apparatus, an electric power storage system, an electric power system, and an electric vehicle.
In related art, lithium-ion secondary batteries using carbon for the anode, a lithium-transition metal composite oxide for the cathode, and a carbonic acid ester compound for the electrolyte are in widespread use. Since carbonic acid ester is stable to oxidation and reduction and can provide higher voltage in comparison to water or other organic solvents, lithium-ion secondary batteries configured in this way exhibit higher energy density and higher capacity than those of nickel-metal hydride batteries that are aqueous batteries. For this reason, lithium-ion secondary batteries are widely used as secondary batteries for electric tools, notebook PCs, portable telephones, camcorders, digital still cameras, and so on.
In recent years, other than the above-mentioned applications, lithium-ion secondary batteries are also growing in popularity for industrial applications such as electric automobile and electric power storage applications. Performance features desired for industrial secondary batteries include high capacity, high output, and long life. One of the performance features that make it possible for a battery to withstand large current is heat dissipation property. A battery generates heat when applied with a large current. It is recognized that an excessive rise in battery temperature hastens degradation of battery performance, and leads to shorter battery life. Accordingly, an important consideration is how to efficiently dissipate heat generated by the battery. Various studies and investigations have been conducted in this regard.
The construction of a battery module in which a number of cells are contained within a case is disadvantageous from the viewpoint of heat dissipation. Accordingly, Japanese Unexamined Patent Application Publication No. 2007-280858 describes a battery module whose cells are not contained within a case.